Diseases caused by filamentous fungi are a concern for both agriculture and human health. Patients who are immunocompromised are especially at risk for frequently fatal fungal infections. This population has increased with advances in medical technology. Fusarium oxysporum is a fungal pathogen of plants and animals, including humans. A single isolate of F. oxysporum, capable of infecting the wax moth caterpillar Galleria mellonella and the plant Arabidopsis thaliana, will be used to identify fungal genes necessary for the pathogenesis of an animal, a plant or both hosts. The latter multiple-host virulence genes may reveal targets for broad spectrum antifungal drugs, pesticides or treatments. The proposed work entails five steps: generation of Fusarium mutants by insertional mutagenesis; identification of Fusarium mutants with reduced virulence in multiple host assays; confirmation of role for mutated gene in pathogenesis; and assignment of identified gene to a specific role in pathogenesis.